The present invention relates to an indexable cutting insert for chip cutting machining comprising a body of generally polygonal shape having an upper chip face, an opposite planar bottom face and side surfaces therebetween intersecting the upper chip face to define main cutting edges therewith. The invention also relates to a 90.degree. shoulder mill equipped with such indexable inserts.
A prior art insert of the afore-mentioned type to be mounted in milling cutters of radial negative and axially positive cutting angle is disclosed for instance in Swedish Patent Publication No. 419,834, corresponding to U.S. Pat. No. 3,955,259. When milling with such inserts is carried out, however, the chip formation has not always been satisfactory under certain conditions. Also, with such milling cutters the desired cutting depth has not been achieved, especially with 90.degree. shoulder mills, due to the fact that the required large positive chip angle could not be used with such inserts having four main cutting edges.
It is an object of the present invention to provide an indexable cutting insert that enables 90.degree. shoulder milling operations to be carried out with a positive chip angle. A further object is to provide such an insert which has four indexable cutting edges.
It is another object of the invention to provide an insert that reduces the energy needed for its engagement with a workpiece.
It is yet another object of the invention to provide an insert whose lifetime can be maximized.